1. Field of the Invention
The invention relates to a document image processing apparatus and, more particularly, to a document image processing apparatus such as an enlarging reading apparatus or the like for enlarging a document for a visually impaired person and for displaying the enlarged document image.
2. Related Background Art
According to the fact-finding survey of February in 1987 by the Ministry of Public Welfare in Japan, the number of physically handicapped persons (ages: 18 or more) in Japan is equal to 2,400,000. Among them, the number of visually impaired persons is equal to 307,000, which corresponds to 12.7%. Among them, the number of persons who are employed as full-time workers in the whole country of Japan is equal to 17,000, which corresponds to at most 5.5% of the whole number of visually impaired persons.
The ability of a visually impaired person to read printed or written characters is considered to be one of the largest hurdles to overcome to more fully participate in the mainstream of society. Societal participation is significantly effected by the ability to communicate with written or printed characters.
There are two methods to overcome this handicap: that is, a method of improving the eyesight function itself having a handicap, and a method of substituting the eyesight function by an auditory sense, tactual sense, or the like in the case where the handicapped function cannot be assisted.
In the former method, when a visually impaired person sees characters or a diagram/table, the eyesight can be improved by using lenses (glasses). Further, characters or a diagram/table is photographed by using a video camera or the like and is subjected to an electrical process and the characters or diagram/table is enlarged, thereby enabling the characters or diagram/table to be easily seen.
FIG. 5 is a block constructional diagram of a Vantage.RTM. (registered tradename) made by Telesensory Systems, Inc. of U.S.A. as an example of the enlarging reading apparatus.
The enlarging reading apparatus comprises: a lighting device 52 to light a document 51; a camera 53 to photograph the document 51 lighted by the lighting device 52; a processor 54 to process the image of the document 51 photographed by the camera 53; and a display 55 to display the document 51 whose image has been processed by the processor 54.
In the enlarging reading apparatus, an illuminating light 56 from the lighting device 52 illuminates the document 51 put on a platen 57. The document 51 is photographed by the camera 53. The image of the document 51 which has passed through a zoom lens (not shown) of the camera 53 is converted into the video electric signal by a vidicon (image pickup tube) or a CCD (charge coupled device) and supplied to the processor 54. The processor 54 scans onto the display screen and performs image processes such as deletion of unnecessary portions by masking, adjustment of the brightness and contrast of the display screen, inversion of black and white on the display screen, and the like are executed on the video electric signal. In accordance with the above image processes by the processor 54 or by a combination with the display size, the document image of preselected magnification (for instance, 3 to 45 times) based on the degree of visual impairment is displayed on the display 55. A green or amber CRT (cathode ray tube) of the 14-inch size is used as a display 55.
The above conventional enlarging reading apparatus (document image processing apparatus), however, has the following problems. That is:
(1) Electric power consumptions of the lighting device and the display are large and a usable power source is limited to an AC power source. PA1 (2) Since the CRT is used, a weight of apparatus increases and the apparatus is poor in portability. PA1 (3) Only the image of the document which is at present being lighted by the lighting device is displayed on the display and the photographed document cannot be preserved. PA1 (4) Since the document is mechanically moved by the movement of the platen, it is difficult to move the document at a high speed.